1. Field of the Invention
The present invention concerns a method of marking objects that is impossible to forge and is visible, providing good contrast and better visibility of marking, and the objects marked in this way.
2. Background Information
The present invention applies to, among other objects, marking labels used for livestock but can have other applications.
The marking of livestock is performed by fixing one or two labels to the animal""s ear. The label carries marking constituted by signs and/or figures and/or letters, part of which is used by the farmer to identify the animal in the field.
It has appeared necessary for these numbers to be indelible so as to be tamper-proof and so as not to serve as a medium for fraud. The label carrying the marking is generally made of a known type of synthetic material.
The indelibility of the marking has been achieved to date by the use of laser, which has the effect of producing marking within the body or the thickness of the sheet constituting the label. However, this does not give accentuated contrast in comparison with the colour of the label; hence, reading from a distance is limited. Therefore, in France where labels are salmon-coloured for cattle, the use of laser engraving gives marking that is grey in colour.
The present invention aims to obviate these drawbacks.
To this end, the method according to the present invention of marking objects that is impossible to forge, is indelible and has contrast, is characterised essentially in that the marking is performed in two operations, marking within the body, i.e. within the thickness of the object, and surface marking superimposed over said marking within the body.
According to yet another characteristic of the invention, marking is performed in two operations, marking by modifying the structure of the object by a thermochemical phenomenon, and a surface deposit.
According to another characteristic of the invention, the marking within the body is produced by laser engraving and the surface marking superimposed over the former is produced by inking, for example according to what is known as the ink-jet technique; or the other way round, i.e. the surface marking is added first and marking within the body, for example by laser engraving, is performed subsequently.
According to yet another characteristic of the invention, marking within the body is produced by spaced-out lines defining the contour of each sign, letter or figure, for example, between which a space is left, which is covered by the surface marking. Preferably, according to another characteristic of the invention, the lines are parallel.